ChaCha22 constructor

Implementation

ChaCha22({
  required this.key,
  required List<int> nonce,
  int nonceInplaceCounterLength = 0,
}) {
  // We only support 256-bit keys.
  if (key.length != 32) {
    throw ArgumentException.invalidOperationArguments(
      "streamXOR",
      name: "key",
      reason: "Invalid key bytes length.",
    );
  }

  List<int> nc;
  int counterLength;

  if (nonceInplaceCounterLength == 0) {
    if (nonce.length != 8 && nonce.length != 12) {
      throw ArgumentException.invalidOperationArguments(
        "streamXOR",
        name: "nonce",
        reason: "Invalid nonce bytes length.",
      );
    }
    nc = List<int>.filled(16, 0);
    counterLength = nc.length - nonce.length;
    nc.setAll(counterLength, nonce);
  } else {
    if (nonce.length != 16) {
      throw ArgumentException.invalidOperationArguments(
        "streamXOR",
        name: "nonce",
        reason: "Invalid nonce bytes length.",
      );
    }
    nc = nonce;
    counterLength = nonceInplaceCounterLength;
  }
  this.nonce = nc;
  this.counterLength = counterLength;
}